What is the difference this 2 sample pictures? Use IMAQ Detect Circles function to detect the GREEN button.

Question

Hi All,
Please refer to the attached 2 pictures, they are the similar, just the size is defferent. (pass.PNG, 5478 pass.PNG).
But now i try to use IMAQ Detect Circles to catch the GREEN button. For pass.PNG, it works fine, but for another sample, it is always fail to detect this button. 
I also try to change the Curve Parameters and score as input, but still failed. Another way, i also try to use IMAQ find circles function, but the result is worse than IMAQ Detect Circles, so give up. 
The code is detect the circles.png, copy it to block diagram enough.
So, what is the root cause? Thanks for help.
Colin
LV7.1/8.2/8.2.1/8.5/8.6/9.0/2010/2013; testing system development
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Attachments:
pass.PNG ‏38 KB
5478 pass.PNG ‏35 KB
detect the circles.png ‏112 KB

Answer 1

Hi colinzhang,
The curve extraction mode if change it to Uniform mode, u can get the result.
-Suggestion, if you want to use the entire image region as ROI no need to get the image size, getting rectangle and converting it to ROI descriptor. (I think this is unnecessary)
-Be careful with color plane extraction, u're using by default which is Red plane. In this example it's fine. but make sure u know which plane u're extracting.
-please find vi saved in 2010 version.
Thanks
uday,
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Certified LabVIEW Associate Developer (CLAD) Using LV13
Attachments:
Detect_Circles.vi ‏53 KB